Safety voltage detector



Jan. 29, 1957 A. E. WEST SAFETY VOLTAGE DETECTOR 2 Sheets-Sheet 1 Filed March 16, 1953 u s me U M .a mw N m l R J ma u, o l l l 1 l l l 4l nim- T T .|r||||i|l||l||||||l||||l| R T u e A a L A V. B -D F e r liiliifrlir .,.Hve lllilz: w 6 8 ,.5 w 2 2 3. EL

Jan. 29, 1957 A. E. WEST SAFETY VOLTAGE DETECTOR 2 Sheets-Sheet 2 Filed March 16, 1953 INVENTOR.

ALBERT El. WEST BY .man1/rub( ATTORNEYS United States Patent O firce SAFETY VOLTAGE DETECTOR Albert E. West, San Francisco, Calif.

Application March 16, 1953, Serial No. 342,635 1 Claim. (ci. 324-725) An object of my invention is to provide a safety voltage detector which is an improvement over my patented device, Patent Number 2,500,725, issued March 14, 1950. In the p atent I show a portable safety voltage detector comprising two staffs for the purpose of checking the line wires and other live contacts to see whether a current at a high voltage is passing through the wires before the lineman starts his work. The main staif is provided with a neon lamp and the lamp is electrically connected in a circuit that extends from the main stat to the auxiliary staff so that when the two staffs contact two high tension lines, the neon lamp will be energized if a high voltage current is flowing through the lines.

The current flowing through the patented device is insulated from the outer surfaces of the device so that it cannot reach the operator. Furthermore, any creepage current flowing along the outer or inner surfaces of the patented device, willbe carried to ground before it can reach the operator. This arrangement permits the patented device to be used in rainy Weather with safety.

Safety regulations require two linemen to work on a pole or when contacting or handling high voltage circuits or equipment. One man would handle the main staff and the other man, the auxiliary sta.

An object of my present invention is to provide a safety voltage detector in which both stals carry neon lamps and in addition both stads carry kv. voltmeters. When therefore a live line or equipment is contacted by a lineman holding the auxiliary staff, he will notice a glow in the neon tube on his staff and at the same time the lineman holding the main staff will notice a glow in theneon tube on his staif, thus indicating to both men that the line or equipment is alive.

In phasing out lines or equipment, one lineman contacts one line or equipment with the auxiliary stati and the other lineman contacts another line or equipment with the main staff and both men will notice a glow in the neon lamp on his stat and a voltage reading from the kv. meter on his staif which will indicate whether the lines orequipment are on the same phase or a different phase.

Each lineman receives the same check from the neon lamp on the condition of the line or equipment and in addition, a voltage reading when both staffs are contacted to the line or equipment and each lineman can satisfy himself as to the condition of the line or equipment and convey his information to a foreman on the ground who in turn thus receives a double check on the condition of the line or equipment being tested. The neon lamp will be partially energized and will glow when the staff to which it is attached is brought into the vicinity of a high tension wire in which a current is flowing. When both staffs actually contact the high voltage wires, the neon lamps are brought up to full brilliance.

The wire that interconnects the two staffs, carries no more than approximately one milliampere at any time regardless of what voltage exists in the lines being tested. Itis known that a sixty cycle A. C. current of nine milliamperes is safe to handle. The neon lamps and the kv.

u 2,779,919 Patented Jan. 29, 1957 meters are each provided with shunt resistances, so that in case of failure of either lamp or either meter, the remaining electrical indicators will continue to function.

Other objects and advantages will appear in the following specification, and the novel features of the device will be particularly pointed out in the appended claims.

`My invention is illustrated in the accompanying drawing forming a part of this application, in which:

Figure l is a side elevation of the main andtauxiliary staffs shown electrically connected and provided with a ground wire;

Figure 2 is an enlarged section taken along the line II-II of Figure l; t

Figure 3 is a sectional view through one of the staffs; and

Figure 4 is a wiring diagram of the electrical circuit used in the device.

While I have shown only the preferred form of my invention, it should be understood that various changes or modifications may be made within the scope of the appended claims without departing from the spirit and scope of the invention.

In carrying out my invention, I provide a main `staff indicated generally at A in Figure l and an auxiliary staff indicated generally at B. In Figure 3, a vertical section through the auxiliary statt B is illustrated and since both staffs are substantially identical in construction, a description of the auxiliary staff B will be given and similar parts in the staff A will be given corresponding numerals to the parts in the staif B, except that the numerals for the parts inthe staff A will be primed.

A An insulating tube 41 forms the main bodylfor the auxiliary stal B and Figure 1 illustrates `the insulating tube 1 for the main staff A. A metal hook 2 is placed at the top of the body 1 for the auxiliary'statf B and an electric terminal 3 is placed at the top of the body 1', for the main stai A.

The body 1 carries an insulating shoulder 4 that is placed below the upper end of the body. A petticoat insu lator 5 is positioned under the shoulder 4.` lshow a triple petticoat insulator in Figure 3, and this type is used where the staffs are to check high tension lines ranging from two to thirty-tive kilovolts. Where linescarry from two to twenty-tive kilovolts, a double petticoat insulator will be used rather than the triple petticoat one illustrated. A single petticoat insulator is used on staffs checking high tension lines from one to fifteen kilovolts and where the voltage in the lines runs up to seventy kilovolts, two triple petticoat insulators are used, one being disposed above the other on the body 1.

A base `6 is placed below the petticoat insulator 5 and this base carries a kv. Voltmeter 7 and a neon lamp 8. The voltmeter 7 is a one millimpere ammeter calibrated in kilovolts. The neon tube has a light output of about` three thousand hours. The kv. voltmeter is mounted in a casing 9 and the neon tube is mounted in a casing 10. Both casings permit the reading of the current indicators 7 and 8 by a person holding the lower end of the tube 1 and looking upwardly toward the top of the tube.

An internal electrical barrier 11 made of insulating material is mounted within the tubular body 1, Asee Figure 3. An electrical ground collar 12 is attached to the outer surface of the body 1 near the hand grip portion B1 of the body. An inner metal ring 13 is placed within the tubular body 1 and the collar and ring are ,held in place and electrically connected together by a bolt 14 and a wing nut 15. An insulating shoulder 16 is placed just above the collar 12 and a second insulating shoulder 17 is placed just below the collar.V Theshoulders 16 and 17 are large enough to prevent an operators hands from touching the collar 12. Y

3 Referring. t@ Figura, 1, is` will. be .Hated that aa arteasion insulating handle 1S can be slipped over the lower end of the body 1 for increasing its length where desired. The top of the extension handle will contact an insulating Sleeve 1.9 that in. turn abats` tha, uadersurfaaa at @ha shoulder i7. Thegextension sleeve is removably held in place by a. sat screw 2,0 which passes thrgush ali Opening (not shown) in the body 1 and is received in a threaded opening 21 provided in` an insulating petition 22,.

Both `staffs A and B are V,electrically connected together by a cable 23, that extends from a socket 2i in the base 6 of the auxiliary. staff B, to a socket 25; in the base 6' of the lmain staff A. The cable 23isten to ,fifteen feet or more in length and is enclosed in an insulating rubber tube 25. lt is possible for a lineman to grasp the main staff A, and a second lineman to grasp the auxiliary staff B, and each man ,-be fr ee Ato move up to ten to fifteen feet away from each other when testing high voltage lines or other equipment.

n Figure 1, I show a ground wire 2,6 with a clamp 27 adapted to removably grip the collar 12. A second clamp 2S, connected at the other end of the Wire 26 is used for grounding the wire such as to a metal object 29. The two staffs -A and B have their collars 12 and 12, respectively, electrically interconnected by a wire 3,0 that is connected to the clamp 27 at one end and has its other end provided with a clamp 31 that is removably secured to the collar 12' on the rnain stati A.

Any stray electricity that creeps d own the outside or inside of the. tubular' bodies 1 and 51' is picked up by thel collars 12 and i2 or rings 13. and 13. Vand is conveyed by the wires 30 and 26 to ground before it can reach the hand grip portions A and B', or the extensions 18 and 18 if used. The petticoat insulators and 5 provide a dry space within the insulators to prevent the externalcreep ing of electricity down along the outer surfaces of .the statfs A and B when they are used in rainy Weather.

It is best now to describe the wiring diagram of Figure 4. A resistor 32 is electrically connected to the hook 2 and is housed within the upper portion of the tubular body 1. Another resistor 32 is electrically connected to the electric terminal 3 and is housed within the upper portion of the tubular body 1'. Each resistor 32 and 32 is approximatelyV eighteen megohms. A wire 33 leads from the resistor 32 to a Calibrating resistor 34 of approximately four megohrns. A wire 33 connects theV Calibrating resistor with the'kv. voltmeter 7.

It will be noted from Figure 4, vthat a by-pass resistor 36 of approximately 70,000 ohms is shunted across vthe kv. voltmeter 7V and carries the electric current if for any reason the Vvoltrneter should fail to operate. The by-pass `or shunting resistoris housed within lthe same casing 9 that houses the voltmeter 7. A wire 37 electrically connects the neon tube S with the kv. voltmeter 7 so that the two are in series with each other. Also a by-pass resistor 33 ofapproximately five megohms is shunted across the neon tube 8 and carries'the electric current'ifv for any reason the neon tube should fail to operate. The by-pass resistor 38 is housed within the casing 10; i

The cable 23 electrically connects the neon tubes 8 and 3 together in series. Figure 4 further shows the ground collars 12 and 12 interconnected electrically by the wire 30, and lthe wire 26 leads from the collar i2 to ground 29. When the staffs A and B are connected to high tension wires, current will ow from the hook 2, through the resistor 32, Wire 33, and Calibrating resistor 34. From here the current will flow through wire 35 to kv. .voltrneter 7 and on through .wire 37 to the neon tube 3.

Since the main .staff A .is electrically connected vto the auxiliary statfby the Wire 23, the current will ow from the neon tube S tothe neon .tube 3 and thence through the wire 37' to the kv. voltmeter 'I' and o-n to the electric terminal 3 by means of the wire 35', `ealibrating resistor 34', wire 33', and the resistor 32. In case either one of the kv. voltrne'ters 7 and 7' and either one ofthe neon tubes 8 and 8 should burn out, the by-pass resistors 36, 38, 33' or 36', would permit the current to be shunted around the burned out electrical indicator and thus the remaining electrical indicators would continue to function.

The safety voltage detectors provide the maximum protection against dangerous high voltagecurrent in both dry and wet weather. The high voltage current is reduced to a low non-hazardous value at the top of the two staffs so that the linemen do not handle high voltage current at any time. The safety voltagedetectors combine hot sticks leads for testing potential transformers and meters. lhasing and other tests on lines or equipment having voltages from 1G00 to 70,000 volts A. C. at twenty-five cycles to one hundred and thirty-three cycles can be carried out.

The device can be used in dry or cramped locations, as in manholes -or on unsheathed'cables or on outside lines in the rain, `snow and ice conditions. In wet or moist weather, the`- extension handles 18 and 18 areput'on the handles B' and A', respectively. This gives ya longer reach. When the device is used in dry weather, it is not necessary to use the extension handles, nor is it necessary to use the ground wire connection.

When either staff is brought near a line or other equipment that has a high voltage current therein, the neon tube will glow even before contact is made. This will Warn the operator that he is in the vicinityA of high'voltage current'andcaution should 'be exercised. As soon as Contact is made with the two staffs, the neon tube will increase -to f ull brilliancy. At the same ytimel the 'kv. voltrneters will'givedthe exact reading as to the number of volts in theV lines or `in the equipment being tested.` The two kinds of electrical indicators are each lindependent of the other. Yet the neon'tube gives the initial"*warning by glowing before contact is made andtheri the kv. voltmetcrs will give an'accurate reading in volts after contact is made. The total electrical resistance of onestaff plus the total' electrical resistance of the other staff will cause a negligible amount of current to ow through the line 23 thatY interconnects the'staffs. i i i A d owel pin 3,9 is used for securing the bushing 24 and the rubber tubing`25 to the base 6. The dow'el'pin penetraites the baseibushing 24 and the rubber tubing 25, to hold them all in place on the base ,6i 'v lnA actual practice, the resistors 32 and 32 are sealed in a high Adielectric insulating tube,- not shown, and the tubes are' placed withinthe upper portions of the hollow statfs 1 and 2. The lplacing of a resistor 32 in Vthe staff B and a resistor 32' in the staff A results'in an approximately equal yamount of resistance being placed within each staff, thereby addingianV Aadditional safety feature in case human contact is made with the high voltage cable'23 ythat extends between the Atwo staifs. f

A safety voltage detector for high Voltage lines and the like comprising a main staff, an electrical ter'niir'ial `ar ranged at the top 'of' the staff and adapted to contacta ground or a high tension wire havingelectrici-ty of a certain phase vflov'ving therethrough; a resistor mounted in the vstaff and being electrically connected to the terminal; a lcv. voltrneter carried `by the staff and'cdnnected in series with the resistor, a second resistor shunted across the veltmeter and designed to carry the electric current should theV voltmeter fail to function; an auxiliary staff, a second electrical terminal arranged at the top ofthe auxiliary statf and adapted to contacta high tension ,wire having a phase of electricity owing therethrough which is different from the "other high tension wireto be een tac'tc'd; a third resistor mounted in the auxiliary staif'and being electrically'crinnected to the lsecond terminaba neon tube carried bythe auxiliary staffand bein'g'con nected in series with the third resistor; a fourth resistor shunted across the neon tube and designed to carry the electric current should the tube failto function; and an elongated flexible wire electrically connected to the voltmeter of the main staff and to the neon tube of the auxiliary staff so that the neon lamp will indicate that there is high tension current flowing through the line when the terminal of the auxiliary staff contacts the line Iand the voltmeter will indicate the voltage when the terminal of the main stai contacts the ground or the other staif.

References Cited in the le of this patent UNITED STATES PATENTS Fuller Aug. 7, 1934 Moore Sept. 28, 1948 West v Mar. 14, 1950 

